Double hung windows are typically positioned in a frame and have a top sash and a bottom sash. The sashes are each positioned in a channel on each side that permits the sashes to be moved from an open position to a closed position. The sash will have one or more panes of glass framed by the sides of the sash.
In many applications the double hung windows are opened for ventilation. Traditionally warm air from a room exits from the opening formed by the top sash. When the top sash is lowered cooler air from the outside enters a room through the bottom sash when that sash is raised.
One of the issues with double hung windows is security. In order to prevent unauthorized ingress or egress through a double hung window, many building personnel and homeowners use sash locks to secure the window from opening. Traditionally, the sash lock has a handle for moving a securing member into and out of a locked position.
One sash, usually the lower sash, has a sash lock secured to the upper surface of the top horizontal member. This lock secures a catch to a keeper positioned on the opposite sash. The keeper is usually mounted on the inside surface of the lower horizontal member of the upper sash.
One of the issues that many users have with sash locks relates to determining whether the sash lock is in a locked or unlocked arrangement. Many homeowners and/or business establishments that have double hung windows have a number of double hung windows on their premises. At any given time some of the windows may be opened and the remainder closed. When a business is closing for the night or a homeowner is locking up the house because he will be away from home for one reason or another, all the windows should be locked for safety reasons. Many homes can have twenty or more double hung windows, each of which must be individually checked to determine if they are locked. Traditionally the user would have to manually check each individual lock to determine whether it is locked or not. This is time consuming and subject to errors by the user. Accordingly, there is a need for an improved sash lock system so that its locked status can be readily ascertained.